


BDSM: A Joint Hypothesis and Experiment

by Zaxal



Category: The Big Bang Theory (TV)
Genre: BDSM, Bondage, Consensual, Contracts, Dom/sub, Established Relationship, Kink Negotiation, M/M, Spanking, Wax Play
Language: English
Status: Completed
Published: 2016-05-05
Updated: 2016-05-05
Packaged: 2018-06-06 13:36:16
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 7,670
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6756337
Author URL: https://archiveofourown.org/users/Zaxal/pseuds/Zaxal
Summary: <blockquote class="userstuff">
              <p>There are undeniable similarities between The Roommate Agreement and a slave contract. Intrigued by the possibilities, the boys decide to experiment.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

  * For [MangoMartini](https://archiveofourown.org/users/MangoMartini/gifts).



> For MangoMartini/impossiblemonsieur; I hope you like it!

>   
>  “I’d like to bite that lip,” he whispers darkly.
> 
> _Oh my_. I am completely unaware that I am chewing my bottom lip. My mouth pops open as I gasp and swallow at the same time. That has to be the sexiest thing anybody has ever said to me. My heart beat spikes, and I think I’m panting. Jeez, I’m a quivering, moist mess, and he hasn’t even touched me. I squirm in my seat and meet his dark glare.

"Oh, please," he mumbled to himself, sourly flipping the bulk of the book over to eye the number of pages he had left to read. It should have been nothing. Simple and easy and over with already, but it had somehow achieved a level of tedium that Sheldon had previously only ascribed to required readings for lesser sciences.

But even those he could power through.

Because those he understood.

But here he was, some 50-odd pages into the _thrilling_ tale of instant, mutual, animal attraction, and he had hit a roadblock. His suspension of disbelief allowed for Jedi and elves, for time travel and evil that could be struck a mighty blow through the power of a strong platonic bond.

Sheldon thought of Samwise Gamgee, standing at the precipice at the end of their harrowing journey, begging his Frodo to throw away Sauron's ring. The spell hadn't been broken by true love's kiss but by Sam's unwavering support and a rather convenient Gollum.

Fairy tales had never held that appeal for him, and he supposed that this was, in a way, following those same lines; well-worn, tried-and-true tropes that he had never connected to the way others did. He'd thought it all a myth or something experienced by more primitive steps in human evolution.

That was, of course, until something similar had happened to him.

\-----

 _Homo novus_ was not supposed to feel irrational jealousy when his roommate began fawning over a new girl, doe-eyed and setting himself up for another heartache. After struggling against it, pushing it aside, and trying to move on with his life, he'd had to come to terms with the fact that it wasn't irrational at all.

And it hadn't been Leonard he was jealous of.

"Would you be open to the idea of making certain amendments to the Roommate Agreement?" Sheldon asked while perusing over the collection of comics for sale, trying to subtly watch Leonard to gauge his response.

"Would I be open to it?" Leonard repeated, staring at him. "What'd I do this time?"

Sheldon set his jaw, trying to think of the best way to delicately broach this sort of subject with Leonard when the idea made something inside him feel jittery, uncertain, unstable. "It's not you. It's her," he said, still dancing out of the way of the true purpose of this conversation.

Leonard rolled his eyes – did he honestly think Sheldon couldn't see him do it? As often as he did? – and sighed heavily. "Can't you just let me have this?"

"Until she breaks up with you and breaks your heart? Certainly not." He glared. "This must be addressed now, before it gets worse."

"Here it comes," Leonard muttered under his breath.

"What?" he snapped without meaning to, feeling like the world was starting to spin faster, like he was already losing control of the situation.

"The list of reasons we're not compatible, the number of reasons she has to dump me, the PowerPoint presentation on my personal failings."

Sheldon hesitated. "I only did that once and-"

"Once was enough." He put the comic he'd been looking at down. "I don't feel like doing this anymore. Buy what you want, and let's go home."

"Leonard, you're not listening to me."

"I've heard everything you have to say." He glared up at him over the rims of his glasses, eyes squinted – as if he could see anything – and mouth twisted into a scowl. "Or am I missing one?"

Sheldon still couldn't find the words, so Leonard shrugged away, gave a careless farewell to Stuart and stepped outside, presumably to get away from him. For the first time in years, Sheldon passed by the counter without buying or asking about a single thing, making a beeline for his roommate outside.

"The amendment I'm proposing-"

"I don't care," he said, sounding tired and defeated, and that usually meant Sheldon was winning but it felt quite the opposite.

"The amendment," Sheldon began again, "would be for our relationship with one another."

"You said it was about Sara."

"Oh, who cares if it's Sara or Joyce or, or-" He stammered, flustered. "Any woman. They all get in the way."

\-----

The memory played itself over in Sheldon's mind, and he could see now what he hadn't seen then – the way Leonard went stiff, the shallowness of his breathing, the way time seemed to stand still and demanded an explanation for it.

Sheldon had plowed ahead, moving straight through his anxiety and to the crux of the matter at hand.

\-----

"Our lives are better without them Leonard. There's a very simple, elegant solution to all of this, but I was blind to it until recently, and I think you'll find it an agreeable alternative to your endless chases after fickle females."

"Yeah?" He sounded so small in that moment that even Sheldon's Vulcan hearing almost missed it.

"Yes," he stressed. "If I were to fill the role myself, you wouldn't need to invite a third person into an already-functioning system, thus potentially changing everything from our dynamic to our furniture."

Leonard's laugh was disbelieving, insincere. "So what? You'll let me touch you? Kiss you?" He peeked at Sheldon out of the corner of his eye. "Make love to you?"

"Don't be ridiculous."

\-----

Leonard had visibly relaxed, which Sheldon now knew meant he'd found the foothold he'd use to keep himself out of his reach, the point where the battle would take place.

He'd turned to look at him, arms crossed, _angry_.

\-----

Sheldon explained, quickly, "Your desires wouldn't be satisfied without reciprocal behavior."

With Leonard looking straight at him, he could see the shock wash over him, the way his cheek went pink as he bit his own lower lip.

Would biting it achieve something for either of them? Was it meant to be pleasurable? The side thought twisted in the winds of his memories then vanished, leaving him with the sound of a door slamming closed and Leonard telling him to get in the car.

\-----

He'd refused to talk about it for weeks. Sara broke up with him. Leonard was sad, as usual, and Sheldon had resolved to repeat his offer, knocking at Leonard's door one night before bed.

\-----

When Leonard opened it, his entire body was shaking and he lifted a hand, fingers delicately resting on Sheldon's cheek. Sheldon froze in the hall, gaping and barely able to breathe. "I thought so," Leonard said sadly and leaned away, bringing his hand down to fidget nervously. "Sheldon, what I want from a relationship – that's not something you want to give. And that's fine. I don't want 'reciprocal behavior', I want someone who wants to touch me and love me even though my list of faults can apparently fill up 20 slides no problem."

"21," Sheldon corrected under his breath, and, in a moment of pure impulse, he reached out, fingers alighting on Leonard's bicep, where his sleeping shirt met his skin.

Time stood still again. "This isn't easy for me. You're right about that." He averted his eyes, but kept his fingers pinned, worrying at the hem of the sleeve, focusing on a loose stitch rather than the confession that he could barely murmur. "But that doesn't mean I don't want it. Or that I don't want to try. You give all these- these _random_ women second, third, sometimes fourth chances unless they're North Korean spies. I'm asking for one."

The silence wasn't too long, but it felt like a lifetime. "Then," Leonard ventured softly, reaching up to cover Sheldon's nervous fingers with his own, his hand warm and steady, "we should go on a date first. Start with the basics."

\-----

That was how it had begun for them, a slow change, a shift in their desires concerning one another, eventually reaching a harmonious conclusion.

None of _this_. He focused on the words again, scowling. He was meant to believe that in a matter of days, Anastasia Steele knew everything important there was to know about Christian Grey, enough to hold their flimsy relationship together for at least another 300 pages.

Part of him wanted to spitefully flip to the last paragraph, read it, and then take the book back to Penny having claimed to read it all. But that would be cheating, and Sheldon didn't cheat. So he settled into his spot and kept reading.

The door opened and then closed much more quietly as Leonard realized he was immersed in something. In his peripheral vision, Sheldon could see him, holding the bags with their takeout, teetering on one foot to lean over and see the cover.

Sheldon closed the book, pointing the cover down towards his lap. It was best if Leonard didn't know about the bet or what it entailed. "You're home early."

"Traffic wasn't too bad, and the restaurant wasn't busy."

"But our food will be cold before it's time to eat."

"We could eat early," Leonard suggested like it wouldn't throw off Sheldon's entire world if he had his food a good thirty minutes earlier than usual.

"We _could_ descend into total anarchy." Sheldon put the book face-down on the table, standing and crossing to the island as Leonard pulled takeout containers from the bag. "I'd rather not."

"Me either," Leonard teased with a smirk. "I'm kinda used to the monarchy."

Sheldon tried to muster up an offended front before giving it up as a lost cause, reaching around his boyfriend to grab his takeout container, murmuring warmly as he pressed close, "Good to know." Smirked to himself on his way back to his spot, not needing to look to know that Leonard was gaping, lost, the way he always was when Sheldon used the allure of intimacy as a weapon. They'd spent so long building up to the point where he felt comfortable enough in the first place, it seemed a shame not to use it now that it was in his arsenal.

He didn't get back to the book for several hours. At first, he read because he wanted to win, but there came a moment, with Christian Grey kneeling between a mostly naked Anastasia's legs, talking about her _scent_ down _there_ , when Sheldon slammed the book closed. His skin crawled, and he'd shoved the book to the far side of the couch, hands shaking with the knowledge of his defeat.

\-----

He hated having to guess at Penny's schedule, but it was a necessity if he was to get that thing out of their home as quickly as humanly possible. Sheldon had even considered leaving the book on the landing outside her door with a sticky note conceding his defeat, but the potential for the book to be damaged had made him hesitate.

It might not be something he liked at all, but it wasn't something of his. Sheldon couldn't treat it badly as it was not his to destroy.

When his sensitive ears picked up the sounds of Penny moving around in her apartment sometime around noon, he scooped the book up from where it lay, scampered out the door and across the hall, knocked quickly, wanting Fifty Shades of Grey to be out of his possession as quickly as humanly possible. Knock-knock-knock. "Penny!" Repeat. "Penny!" Again. "Penny!" He waited, holding the book away from himself as if it might contaminate him.

When she opened the door, he scowled and thrust the book at her. "Take it."

"Did you read it?" Penny asked, watching him carefully as she took the book from him.

"Yes."

"All of it?"

Sheldon silently cursed. "No."

"Where did you stop?"

"On the eighty-second page."

Penny flipped open the book, frowning slightly as she thumbed to the offending passage that had been his downfall. He cleared his throat. "I will endeavor to be a gracious loser as you won the bet."

"I guess I did." She kept flipping ahead, and Sheldon felt the hair on the back of his neck stand on end, not liking her casual dismissal of his admitted failure or the way she seemed to be searching for something in the book. "Here." She stopped at a page with the words 'Chapter Eleven' in bold. "Read the next few pages – you'll know when to stop."

"Penny," he hissed.

"If you read this, you won't have to do anything else." She peered up at him, face unreadable but certainly determined. "The bet will be over."

"And if I can't?" Sheldon practically spat the last word out, hating it, hating her for making him say it.

"You can, sweetie. It's just a contract."

He blinked several times, mind whirring in a fruitless search for the true meaning behind her words. "That's all?"

"That's all."

"Why?"

She shrugged. "Humor me."


	2. Chapter 2

Sheldon was absorbed. If Leonard had been an artist, he would have had time to carve this image of Sheldon out of marble. He hunched over his laptop, one hand on the touch pad and his other elbow resting on the arm of the couch, chin resting in his grip as one finger curled up to cover his mouth. He'd been staring at his laptop for the last several hours, periodically typing a thing or two before he went back to reading, deeply immersed. Leonard hid his smile in his mug and sipped at his tea, keeping a subtle eye on his boyfriend while he pretended to fiddle with something on his phone.

Leonard wasn't stupid. The book had been recognizable at a glance; even Sheldon's quick attempt to keep him from seeing the title hadn't hidden the obvious gray tie against the black background. It wasn't hard to understand why Sheldon would want to hide it. He wasn't overly comfortable with anyone's sexuality, and deliberately reading smut without a plot that otherwise engaged him was something he usually looked down on.

Whatever he was up to right now involved the book. Leonard was almost absolutely certain of that, from the way Sheldon had pulled his laptop closer as he'd come near to the way he hadn't answered any prodding about what had him so enthralled.

Leonard had reached the totally logical conclusion that Sheldon had become fascinated by kink.

Sure, there was a slight chance that he had enjoyed the book and downloaded a .pdf of the second to hide his guilty pleasure, but the odds were so small, they were practically negligible. He might also be looking up something else only tangentially related and therefore hiding his research under the assumption that Leonard catching him reading about Grey's specific make and model of helicopter would somehow tip him off that the book had implanted itself in his mind.

There were a plethora of possibilities, but Leonard considered and dismissed them as quickly as they came. He had also considered and conceded that it might be wishful thinking on his part, but he was fine with that. Fantasies were allowed within the parameters of their relationship, and this one he'd been holding on to for almost as long as he'd known Sheldon.

Leonard didn't have to read the damn book to reach the obvious conclusion that part of him _loved_ Dr. Sheldon Lee Cooper telling him what to do. It was the only reason he had weathered the storm of Sheldon's unbreakable rules, the way he'd let Sheldon play a major role in his decisions, routines, and habits from the moment Leonard had signed himself over. At times, it annoyed him, and, other times, it was insufferable and suffocating, but the fact remained that he kept coming back.

Once Sheldon had become more confident in himself and with their relationship, once he'd learned how to tease and push Leonard's buttons to get what he wanted, it had been so, so easy to link what their dynamic had always been to the concepts of Dominance and submission.

They were caught in a strange limbo, one where Leonard was almost certain that they had a shared interest though neither was willing to voice it for fear of rejection. Kind of like when they'd both admitted to liking slash fanfiction.

The problem was that taking the initiative had to fall on Sheldon's shoulders as it always had when it came to sex. Sure, now Leonard didn't feel bad or awkward for initiating intimacy, but that had only come after they'd made sure it was something Sheldon enjoyed, something he wanted. His comfort always came first, and Leonard couldn't be selfish enough to impose a pressure to perform on a completely new stage without letting him warm up to the idea on his own.

And if nothing else ever came of it, at least he had his fantasies to keep him company.

\-----

There was nothing but radio silence for weeks; Leonard had all but abandoned the train of thought to the same dusty shelf that held most of his kinks that would never see the light of day. Then, one day, out of the blue: "Would you be amenable to an experiment?"

Leonard blinked up from his book owlishly, finding Sheldon watching him. Leonard was immediately convinced that it had to be a trick question – that he would soon find out that he had been a part of another experiment of taste or texture or any number of things without his consent. He tried to think about any number of times Sheldon might have touched his food or been in his room, so caught up in his own confusion that he neglected to answer.

Sheldon raised his eyebrows, an uncertain look overtaking the earnest questioning. "It's a simple question," he insisted, voice softer, almost pleading.

Leonard bit at his lip before answering, "I- I suppose it would depend on what kind of experiment. I haven't been eating moths again or-"

"Oh, goodness, no," Sheldon assured though he didn't sound properly chastised for the previous infractions. However, the next part seemed harder to say, with him shifting uncomfortably in his spot, looking away for the moment it took him to find the words. "It's about us. As a couple."

Anxiety crashed into him. "As a couple?"

Sheldon nodded, one slow and then again, firmly. "Regarding our sexual intimacies."

"I need a little more information, buddy," Leonard admitted, closing his book and setting it on the coffee table. "Is it something you want to stop doing?"

Sheldon shook his head, and he brought his eyes back to Leonard, their tint dark. "It's something I want to try," he said with wavering confidence. "How familiar are you with," he shifted uncomfortably again, trying to fit his mouth around the word that held as many possibilities for failure as it did for success, "bondage?"

"Pretty, uh. Pretty familiar." His hands began fidgeting in his lap. "Not from personal experience, but, I mean, I've- I might have _watched_ , or read, or... thought about..." He pressed his lips tightly together to keep himself from rambling more. Could feel heat flooding his face, certain that he must be as red as the horrible itchy sweater with the word Lenny stitched into it. "Yeah."

"As have I."

Leonard's eyes widened, his breath catching in his throat. Though he'd anticipated this turn of conversation, to hear Sheldon own up to it without obfuscating, without drawing his attention away immediately was somehow sexier than anything Leonard had ever imagined. "Why didn't you tell me?" Leonard breathed.

"I needed to be certain," Sheldon said. "And make preparations. Research, Leonard."

"Of course." He felt lightheaded, like this couldn't possibly be real, like he'd wake up any minute. "You researched kink."

"Well, I was hardly going to rush in all willy-nilly. It's a complex subject that we'll need to discuss in-depth once we've determined if it's something we want to explore."

"You want to try it out?"

"Yes. With you as the submissive and myself as the Dominant. If that's agreeable?"

Leonard took a shallow but steadying breath. "But we haven't discussed limits or safewords or preferences."

"I had considered, but, as much as I love drafting up contracts, it seemed presumptuous to begin without first establishing a mutual desire and enjoyment. I propose that we start simple. I bought some rope with which I can restrict your movement; you would simply tell me to stop if you didn't like it."

"You have rope."

"I _bought_ rope."

"What was it you were saying about 'presumptuous'?" Leonard teased.

"I wanted to do it correctly with as few varying factors from the real thing for the sake of an accurate result."

It suddenly occurred to Leonard that this was more than wishful thinking, more than Sheldon pushing himself to do something for Leonard – this was something Sheldon wanted. He wanted it to work out; he wanted to explore more, if it was something they both liked.

Sheldon wanted to be his Dom.

Excitement bubbled in his chest. "Are we gonna do it now?"

"I was thinking that we might," Sheldon said. "Unless you're opposed?"

Leonard's heart seemed to catch in his chest. "Do we, uh- Should we start? Now?"

"My bedroom. As we haven't discussed it, there will be no punishment for a lack of cooperation, but to minimize the variables-"

Leonard met his eyes evenly, promised, "Sheldon, I will do literally anything you tell me to right now."

He smiled brightly, "That's the spirit." Pushed himself to his feet and began walking around Leonard's chair, down the hallway, and Leonard scrambled to his feet to follow at his heels.

Sheldon held the door to his room open, ushering Leonard in. Leonard drew back and fidgeted with his hands, watching as Sheldon opened up a drawer in his dresser without hesitation, pulling out a coiled length of rope. He paused to inspect it, taking long enough that Leonard almost began to wonder if he'd forgotten that he was here. "No frays," Sheldon murmured, "so it won't give or rub you too badly."

He turned to face Leonard, eyes flicking up from the rope to Leonard's face. "I want to tie your wrists to my headboard."

"And then?"

Sheldon tilted his head slightly, considering, before the corner of his mouth twitched up into a devious smirk. "Let's not get ahead of ourselves, Leonard." He slid closer, one hand lifting away from the rope to cup his chin, tilting his head up for a warm kiss.

Leonard melted shamelessly into it, trying to quell his excitement and nerves by focusing on the familiar movements of their mouths, the way Sheldon kissed, soft and warm and curious, always experimenting, always searching as if he could find some kind of eureka in the margins of their intimacies, in the physical declarations of love.

Sheldon's hand slid down to his shoulder, pushing beneath his jacket and hoodie. "I want these off."

Leonard was slightly embarrassed at how quickly he shed them, shifting his shoulders and pulling at the sleeves while pressed close to Sheldon, unwilling to pull himself away even if it meant taking longer to get to the end goal. They whumped onto the ground behind him, the loss of weight making him feel exposed, cold.

Sheldon's lips curled into a wider smirk. "Someone's an eager beaver."

"Yeah," Leonard said easily, grinning. "I really wanna see what you can do."

"I'll bet you do." With his free hand, he gently pushed Leonard back. "Shirt, socks, and shoes off, too." Leonard obeyed, keeping a curious eye on Sheldon who set to removing his own shirts, folding them delicately and setting them to the side before he sat on the edge of his bed.

Leonard's hands fumbled with the fly of his pants only to hear Sheldon's voice crack through the silence, "Stop." Leonard swallowed nervously and let his hands fall away, pants hanging from his hips. Sheldon patted the bed. "Lay down."

There was a different energy in the air between them. Usually, having sex was about being close, intimate, taking their time and enjoying being with one another. To have sex without that connection felt almost alien.

Sheldon raised his eyebrows questioningly, patting the bed one last time, sending a _hurry up_ message that got Leonard moving, clambering up onto Sheldon's pristine bedding. "On your back," Sheldon answered the question before Leonard could do more than aim a confused look at him, and he obeyed, scooting down on the bed far enough that his hair gel wouldn't rub off on Sheldon's pillows.

If Sheldon was at all touched by the sacrifice, he didn't comment on it, choosing instead to continue instructing Leonard, "Scoot up. You need to be comfortable."

Leonard wasn't, was the thing. An anxious thought bled through the cracks, a worry that this would be unenjoyable, that his fantasy would be ruined with the cold, harsh reality that they weren't suited for this or weren't suited for exploring it with each other.

Then, Leonard felt the rope against his skin and watched, mesmerized, as Sheldon looped it several times around his wrists before bringing the ends of the rope around the middle, forming cuffs as he pulled them taut. "How's that feel?" he murmured, voice breathy, and Leonard shifted his hands, feeling a thrill run through him when there was very little give.

"I can't move," he breathed.

Sheldon shook his head fondly. "Does it hurt? Move your fingers, Leonard."

He obeyed, wriggling excitedly. "Doesn't hurt."

"Do you like it?"

Leonard hadn't expected Sheldon to be so blunt in his approach, but he was, holding the bound wrists and eyes keenly searching Leonard's face. "So far," Leonard said. "You?"

Sheldon didn't answer immediately, setting to tying the ends of the rope to the slats of his headboard. "Pull," he ordered, and Leonard obeyed, feeling that same rush when his hands wouldn't budge more than an inch or two. "Move your fingers." Leonard complied.

He fussed with the ropes a moment longer, testing himself to make sure that it wasn't loose or badly tied. Once satisfied with his assessment, he turned his attention to Leonard, his eyes dark as he moved to straddle him, lips finding Leonard's in a heated kiss. "Yes," he breathed in the intimate space between them. "Lord, yes."

He pressed their hips together, grinding in a slow circle that made Leonard arch, yanking on the rope and whimpering helplessly when it didn't give. Sheldon pulled away, sitting back on his feet and taking in the view, undoubtedly committing even the smallest detail to memory. It was an intoxicating thought, one that he had harbored for years before in secret, thrilling him whenever Sheldon remembered the most menial details about him, proving that somewhere in that massive brain was a special place dedicated solely to Leonard.

Sheldon's fingers slipped into the loose waistband of his pants, running his fingertips along Leonard's warm skin. Dipped down until Leonard's breathing hitched in his chest and then pulling them back out again, looking all-too pleased with himself as Leonard tried to push his hips up.

"You didn't do as I asked," he observed, tugging on the flap of his open fly. "I didn't tell you to start taking these off."

Leonard insisted softly, "Took extra initiative."

"Mm," Sheldon hummed with a smile, "but that's not your place. As a submissive, your duty is to do as I ask unless you know I expect more."

"And what do I get in return?" he teased.

"A reward," Sheldon said, moving his hand farther down, hand confidently squeezing Leonard's dick where it lay hard against his thigh. Squeezed harder, until Leonard groaned out, head falling back. "Or a punishment." When he let up on the pressure, Leonard looked back up at him, breath shuddering in his chest. Sheldon smiled at him, the same smug smile that meant he'd won or been proven right. "You would like that, wouldn't you?"

Leonard's answer escaped not a moment later: "It's not about my enjoyment." Wetted his mouth, feeling on display with every movement he made. "It's about serving you."

The quickening of Sheldon's breath was almost impossible to notice, but the way his hand squeezed Leonard's cock again was a much clearer sign. "Good answer."

Sheldon tugged on his pants, and Leonard lifted his hips to help, wriggling his body as Sheldon pulled the rest of his clothes off and then quickly set about discarding his own, leaving them in a pile on the floor rather than folding them.

In a matter of moments, his body was against Leonard's own, long fingers wrapped around the both of their dicks, lube slicking the way for quick movements, and Leonard had forgotten to ask if he had to get permission to come until the moment he was, hips bucking into Sheldon's merciless pace, over all-too fast, but it wasn't any old day that a wet dream came true.

Sheldon wasn't far behind him, hand moving slickly over his cock, the restless movements of his own hips leading him to thrusting against Leonard's body.

Leonard was so caught up in the rush of post-orgasmic bliss that he didn't register anything as _wrong_ until Sheldon hissed his name like a curse and quickly set to undoing the knots holding Leonard captive. Finally, Leonard realized that his fingers were tingling, his hands otherwise numb.

"You were _supposed_ to tell me if it was too tight!" Sheldon said, letting the rope fall away as he set to massaging one of Leonard's hands.

"It wasn't." Sheldon aimed an icy glare at him. "Okay," Leonard backpedaled, "maybe it _was_ , but I didn't realize it. It's not like I have a lot of experience with this sort of thing."

Sheldon paused to look at him, eyes wide. "You really haven't done this with any of your previous partners?"

Leonard huffed. "No." Looked away before confessing, "None of them really pushed that button for me like you do, anyway."

Sheldon dropped his hand and reached down to turn Leonard's face back up, pressing a heavy, desperate kiss to his lips before he broke away and began tending to the other tingly hand. Leonard couldn't tell if his boyfriend was more flustered at that admission or by the fact that he'd apparently tied him up wrong.

Which did cause a certain question to pop up in his head, "You did that knot really quickly."

"Really, Leonard, criticism? I asked if it was too tight."

"No, I mean... it was like you'd done this before."

Sheldon blinked down at him. "Of course I have. Granted, I couldn't practice with my wrists, but ankles can be tied the same way."

Leonard tried to imagine Sheldon willingly tying his ankles up to his bed and giggled helplessly. "You could've just asked."

" _Apparently not_ ," Sheldon groused.

"Look, Sheldon. Next time, we'll take it slow and make sure that it's good before we get caught up." His heart fluttered. "If you want there to be a 'next time'."

"Of course I do," Sheldon murmured. "I wouldn't have spent money on good rope otherwise. Now, if we're all done, I have to go wash my hands and you have to clean... that." He aimed a distressed look at the mess they'd made on Leonard's body. Before he moved, though, he asked, "Was it good, barring the mishap?"

"Yes," Leonard said emphatically.

"Good," Sheldon sounded so relieved it made Leonard's chest hurt.

Softly, he insisted, "I'm fine. Go get cleaned up."

"Thank you." Sheldon stood up quickly and scuttled towards the bathroom without hesitation, apparently trusting Leonard's word more than his attitude would've led an outsider to believe.

Leonard couldn't help the dumb, doofy grin that spread across his face as he rubbed the rest of the feeling back into his hands.


	3. Chapter 3

"This feels weird with my clothes on."

"Your emotional discomfort has been noted," Sheldon murmured, focusing on the rope as he tied Leonard's hands together. He'd forgone the hoodie and jacket for the sake of accuracy, and his shoes were sitting next to Sheldon's bed, but otherwise, Leonard was completely dressed. And wiggling for no apparent reason. "Stop it."

"Sorry," Leonard mumbled.

"Any physical discomfort?"

"Not yet."

The implication that he might made Sheldon's eye twitch, but he took a steadying breath and finished his knot, testing the give with his own hands rather than letting Leonard take the reins. "Now?"

"No, Sheldon."

"Hmm." There was nothing he enjoyed less than a puzzle he couldn't solve. He had done everything exactly the same – perhaps with fewer nerves – but the problem failed to replicate itself. There was only one variable that wasn't in play, and Sheldon failed to see how sexual intimacies would somehow interfere with his ability to tie rope.

'I don't know' wasn't a satisfactory answer – he had to know.

He leaned down to brush his lips over Leonard's, smirking to himself at the way Leonard eagerly responded. No hesitation, no needless questions. He cupped Leonard's cheek, deepening their kiss. When he broke for air, he took a moment to look at Leonard's face, at the flush on his cheeks and the dark depths of his eyes.

"I thought we weren't going to get up to anything," Leonard teased, grinning.

"I'm experimenting."

"Is that what we're gonna call it?"

Sheldon tore his eyes away to examine the ropework and sure enough, he could spot a loop wrapped tighter around Leonard's hand than it had been moments before. Realizing his mistake, he gave a small agitated huff and set to untying his boyfriend, only to correct his error, looping the rope correctly around itself.

"To answer your previous question," Sheldon murmured with a firm tug, a test that wasn't a good replication, "yes. We are. Unless you have objections?" He spared a glance down at Leonard whose grin seemed to brighten.

"Nope! Experiment away."

Sheldon shuffled down the bed and began kissing Leonard again, his hands already seeking the fly of Leonard's pants.

After all, any good scientist would want to explore more than hypothetical scenarios.

This time, the rope didn't tighten.

\-----

Leonard had a present waiting for him a few days later. He brought in their takeout to see a manila envelope sitting on his chair, his name neatly written in Sheldon's impeccable penmanship. The way his boyfriend didn't mention it was enough to tip him off that it was something quite serious. While Sheldon poked through his order to make sure everything was perfect, Leonard slid into his seat and opened the envelope to find a couple of pieces of paper, still warm from the printer.

There was a box near the top with a key explaining the symbols used to denote Sheldon's interest in a respective, listed kink, or his lack thereof.

Leonard felt his face warm as his food started to cool, unable to tear himself away. Sheldon ate in silence, undoubtedly watching him. "Can I object to any of this?" Leonard asked suddenly, looking up from the paper.

"This is the negotiating phase of our arrangement," Sheldon said. He tried to hide the irritated look on his face, but the clipped tone of his voice gave him away, "What do you have objections to?"

"Paddling." Sheldon's brow wrinkled, but before he could remind Leonard that punishments weren't necessarily meant to be enjoyable, Leonard pressed on. "I don't mind the idea of spanking – I know you do, but it's definitely one I want to try."

"Why on Earth would you _want_ that?"

"The same reason you want to do it to me," Leonard arched an eyebrow, and Sheldon's shoulders hunched forward, defensive. "But I, I don't know. Paddles have always freaked me out. So, no paddles. That's a hard limit."

"Other implements?" Sheldon asked, and as much as he might try to deny it, Leonard could see the depths of his interest. "Such as, but not limited to: floggers, switches, crops, belts?"

A thrill ran down his spine, and he nodded way, way too quickly. "Yeah. Those are fine." Found his eyes drifting downwards to Sheldon's hands as they wrapped around his takeout container. "Hands aren't mentioned."

"Write it in. You are allowed to make additions and subtractions at your leisure."

"When will the negotiating phase end?"

Sheldon blinked at him. "The initial phase, I suppose, would end when we sign the first draft of our contract. My research has led me to the conclusion that we'll always be negotiating."

"Not gonna lie," Leonard murmured. "It's so hot that you did research on this."

"Of course I did research!" He looked utterly scandalized. "Haven't you?"

"Not as much as you, apparently."

Sheldon rolled his eyes. "I'll compile a list of websites and blogs for you to read after you eat." He pointed at the island, at Leonard's own cooling food with his chopsticks. When Leonard didn't obey immediately, Sheldon felt the need to ask, "Would it help if I were to imply that I find you more attractive for having done your homework?"

"It certainly wouldn't hurt. Unlike some of the things on this list." He reached for a pen on the end table nearby and wrote 'No paddles' under the subsection 'Punishment'. 

It was the first change of many.

\-----

Sheldon had thought Leonard was wrong. It wasn't that he wanted to hurt him – it was simply part of the dynamic, part of the character and scene. He didn't dislike the idea when Leonard had broken Sheldon's rules for years without a punishment that truly stuck. He wasn't going to take joy out of addressing the issues that he'd allowed to lie dormant or punishing Leonard's behavior within the containment of the scene.

But this wasn't Sheldon being pulled around by his drunken father, a belt slapping across his butt before he'd had time to brace for the impact.

This was something they'd talked about, something they'd agreed on that had led Leonard to bending over Sheldon's lap, hands gripping the bedspread as the first blow fell from Sheldon's hand.

The moment the slap resounded in the room, he felt something stir in his chest, uncertainty bringing him to a standstill until Leonard spoke, his voice barely a whisper, "Harder."

"How much?" His own voice was husky, demanding.

Leonard answered almost instantly, "20%."

The next slap cracked through his hand, against Leonard's flesh. Sheldon held his breath, watching as Leonard rocked forward onto his arms, shuddering out a breath. "Color?"

"Green," he said, voice rasping as he pushed himself back into place. "Do a set."

On impulse, he reached out with his other hand, steady on Leonard's lower back, feeling something deeply possessive gnarl in his chest as Leonard arched towards his touch and then held still, waiting.

They'd agreed on sets of five. He flexed his hand in anticipation, took a breath, and slapped forward onto Leonard's previously-untouched cheek.

Leonard rocked forward with the blow before pushing himself back, something trembling down his back, and once Sheldon heard him take a deep breath, he continued, spreading the hits evenly between the two cheeks.

On the fourth hit, Leonard released the breath he'd been holding, a soft 'Ah' breaking the silence and igniting a reaction Sheldon had never considered. The hand on Leonard's back pressed down harder, steadying him as he delivered the last and hardest blow. Leonard didn't disappoint, groaning quietly at the impact and then again as the hurt sank in, his pale skin turning pink.

Sheldon wanted to do more. He wanted to see Leonard's backside on the verge of being red, wanted to hear every uncensored reaction Leonard might have to the pain. He wanted to engrave it in his mind so that it never left.

He pulled Leonard up clumsily, pressing a hasty, messy kiss to his mouth. Leonard clambered up into his lap, pressing forward, and the realization that he was hard in spite of the punishment or, likely, because of it made a possessive snarl grasp at his chest as Sheldon pulled him close, hands falling to his ass and kneading roughly as Leonard whined and pushed back into his hands.

Sheldon experimentally pulled his cheeks apart and Leonard gasped, begged, pressing his mouth to Sheldon's throat. "Fuck me. Please, god, I want you to fuck me."

Sheldon's lips curved into a sharp smile, hidden from Leonard's view. "On one condition."

"Anything."

He leaned in, nuzzling Leonard's temple, murmuring into his ear. "You take two more sets."

Leonard's breathing hitched. "And if I don't?"

"We'll stop," he said calmly, "and you won't get a reward."

Leonard made a noise in the back of his throat, a high, pathetic whine as his fingers pressed in, clinging to Sheldon.

Then, in an instant, he released his grip and situated himself back across Sheldon's lap. Sheldon ran an affectionate hand down Leonard's back as he folded his head into his arms.

"Color?" he purred.

"Green."

\-----

Leonard liked being tied up. Not just his hands to Sheldon's headboard, but his arms, torso, thighs, ankles; the first time he flexed in his bindings to find that he was completely immobile felt like the hottest thing he'd ever experienced.

Pun not intended.

" _Shit!_ "

The patter of wax on his skin made him go tense, never quite prepared for the impact until it returned, bringing heat to untouched parts of his body or layering it in specific spots until Leonard felt like he might catch on fire himself.

He thrashed feebly but barely moved at all, and when he stopped, he found Sheldon eyeing him, quirking an eyebrow. "Are you done?"

"G-give me a second." Both of Sheldon's eyebrows raised and Leonard whined, "Please."

With a put-upon sigh, Sheldon set the candle to the side. "Very well." With his warmed hand, he reached down, wrapping Leonard's cock in his long fingers, stroking him softly back to full hardness from when he had flagged slightly from the pain.

"Would you like to climax?"

"Yes," he breathed, hips flexing up off the bed towards his touch, the relentless movements enough to arouse though not push him to the end.

He could see Sheldon's profile, the way his lips quirked into a smirk, his eyes riveted on Leonard's dick though his attention was certainly on the scene. "Would you like to earn it?"

"How?"

Sheldon tutted but didn't stop playing with his cock. "I ask the questions, you give me answers. Or do you need to be reminded?" His eyes slid up to Leonard, smirk widening.

"No, I understand. Loud and clear." He swallowed nervously, a moan building in his chest, released on a wheeze of air before he answered: "Yes. I want to earn it."

"Good boy," he said warmly and released him, letting Leonard catch his breath as he reached again for the candle.

This time, he held it closer to his body, the heat spiking deeper into his skin, hotter, painful, and Leonard bit his lip to keep from crying out, his body tense and shaking with the effort of trying not to move. His eyes slipped closed, taking deep breaths between every series of drops that hit his skin, formed lines and circles, a pattern that didn't make sense until he tried to think about the picture as a whole.

His brow furrowed. "Is that Gallifreyan?"

"Yes. Can you read it?"

"No."

"Do you want to know what it says?" He trailed his fingers over the cool, stiff wax. "What is being burned into your skin? Branded, if you will."

His head fell back on the pillows, having an idea but needing to hear it said aloud. "Yes. Please."

Sheldon's hands were gone for a moment and then fingers buried in his hair, pulling him off the bed. Leonard blinked open his eyes, meeting Sheldon's without flinching. "It says 'Sheldon's'." His lips immediately pressed against Leonard's, heated and hungry, devouring the desperate noise that tore from his throat.

Even knowing the marks would fade, that when this was over, Sheldon would rub lotion on them to help them heal faster and lessen the pain he was currently in – the idea of Sheldon marking him, claiming him, owning him made Leonard feel like he was on fire in the best possible way.

"Please," he murmured, begged, prayed, "please, please."

"Are you mine, Leonard?"

He nodded desperately, narrowly missing knocking their heads together. "I can't hear the movements of your head."

"Yes. God, fuck! Yes, of course I'm yours. All yours."

"Forever," Sheldon breathed, begging himself albeit from a much more advantageous position.

"Forever," he affirmed, nuzzling against Sheldon, heedless of the sweat or heat and reveling when he pressed into it, invited further intimacy for just a moment before snapping back into action.

Sheldon plucked the lube off the end table, next to the flickering candle. He snapped on a sanitary glove and slicked the fingers as he slid down Leonard's body, probing gently until he finally eased the first into his body.

"I'm going to watch you climax, Leonard," he informed him, stroking against his prostate and watching as Leonard arched, struggling against the binds as his cock bobbed in the air. "And I want you to tell me who you belong to while I do."

"Sheldon," he breathed, chest heaving for air already. "I'm yours, Sheldon. Sheldon, Sheldon." By the time Sheldon worked him up to an orgasm, he was incoherent, babbling, gasping, moaning, "Yours!" He arched against what little give there was to the ropes, shaking as Sheldon pumped his cock through his orgasm.

And only then did he hear the rip of a condom package and the feeling of his boyfriend, lover, and Dominant splitting him open so perfect and deep that it was all he could feel, all he could think about besides the affirmation, growled into his ear: "Mine."


End file.
